Ammunition



and are subject to mass detonation.

Patented Aug. 24, 1943 AMMUNITION Gordon M. Calhoun, Bridgeport, Conn, asslgnor to Remington Arms Company, Inc., a corporation of Delaware No Drawing. Application August 8, 1940,

Serial No. 35l,919

7 Claims.

This invention relates to priming compositions for ammunition, and particularly to means for improving the stability and workability of priming compositions made by an admixture of ingredients including lead hypophosphite.

The conventional ammunition priming mixture contains a. reaction-initiating explosive, a fuel and an oxidizer. These materials may also be supplemented by a means to sensitize the explosive and a frictionator, such as ground glass, to assist in the ignition of the composition when it. is struck by a blow.

When lead hypopho'sphite and lead nitrate are placed in a priming composition and the composition is wet or moist, a reaction takes place to form a double salt, which may be' called lead nitrato-hypophosphite, in accordancewith the patent to Brun, 2,116,878. The usual way of loading the conventional rimflre shell, for example, is to place the priming mixture in the shell in a wet pasty form.

Other of the alkali metal or heavy metal salts of nitric and hypophosphorous acid may also be used, thereby forming an alkali metal or heavy metal double salt.

Lead nitrato-hypophosphite is very sensitive to a blow. It has been found, however, that priming compositions containing lead nitrato-hypophosphite are unstable under some conditions Mass detonation may be said to be the substantially simultaneous explosion of a large number of' shells caused by the explosion of a spaced adjacent shell, there being no direct blow given the first-mentioned primed shells.

It can be seen that this is a particularly undesirable property because in a place where a large number of primed shells are being dried or loaded and are relatively close together, the explosion of one shell may set off a large number of shells, with a resultant explosion of considerable force and destruction of the shells.

For some reason that is not exactly known, the lead nit-rato hypophosphite double salt becomes unstable in storage, particularly in the presence of high humidity.

The lead nitrato-hypophosphite double salt also tends to lose its sensitivity in warm; moist air. It is known that the wet lead n'itratohypophosphite, when placed in a conventional rimfire shell, will tend to lose lead hypophosphite,

and it might be that this accounts for the loss in sensitivity. Even after the mixture has been promptly dried after priming, the exposure of the lead nltrato-hypophosphite to warm, moist air will result in the mixture taking up moisture with a consequent loss in sensitivity and stability.

Many of the conventional rimfire shells contain copper, and it appears that the copper acts as a catalyst in the destruction of lead hypophosphite, although it is not certain that this is the case, and it is known that some destruction takes place'even when copper is not present.

It is also possible that the substances added, which improve the stability, serve as antioxidants and therebyprevent the destruction of the lead nitrato-hyophosphite, although this is filled with the priming mixture.

'propriate knockout pins are passed through the holes to force the pellets formed in each hole out of the hole and into the shell, gravity being depended upon to complete the movement of the pellet into the empty shell.

Aproblem that causes difliculty in the loading of lead nitrato-hypophosphite mixtures is an apparent stickiness of the mixture and a tendency for the pellets of the priming mixture to stick to the knockout pins just mentioned instead of falling freely into the empty shell.

The charger plate has the holes therein filled by rubbing the priming mixture into the holes while the plate is resting on a table or other similar surface. The plate is then removed from the table and placed over the shells to be primed. As the charger plate is lifted from the table, the priming mixture will tend to stick to the table and thus some of the pellet holes will havethe mixture removed, with the result that the shells corresponding to the holes having no mixture therein will not receive a priming charge.

The, mixture, because of its stickiness, will also tend to stick to the charger block.

A smal1 quantity of the wet priming mixture containing lead nitrato-hypophosphite may be placed on a piece of glass, and as the mixture is moved back and forth on the glass the mixture willtend to gather in lumps and to follow the article that is imparting motion to the mixture.

The same thing occurs when the knockout pin moves the priming mixture pellet from the charging plate toward the shell, i. a, the pellet sticks to the pin instead of falling into the shell.

It is evident that this willresult in shells that have not had the priming placed therein, with the resultant subsequent failure. of the shell served to both stabilize and to ability of the priming mixture.

to fire after the powder and other components have been assembled thereto.

It is necessary, for successful production of the shells, that the workability of the lead nitratohypophosphite priming mixtures be improved, as otherwise there will be misfires and a slowing up 01' production.

The exact reason for the stickiness or poor workability is not known, although it has been shown that by the addition of the substances of this invention the stickiness is prevented and the shells can be primed properly. The addition of the substances of this invention causes a finer division and inhibits the growth of needle crystals, but whether or not this is the reason for the change in stickiness or workability is not known.

One of the objects of the present invention is parent to those skilled in the art when the following description is read.

Certain of the substances used were found to improve the stability of the hypophosphite and to also improve the workability and preventthe stickiness of the mixture from interfering with loading operations. Other of the substances were found to improve the stability but not materially improve the workability, and still other of the substances were found to improve the workability and not particularly affect the stability. 7 The substances used that will both improve the stability and workability were tri nitro hydroxy benzols, including trinitroresorcin, picric acid, trinitro m-cresol. Trinitrobenzoic acid and hypophosphorous acid were also found to function similarly.

Additional substances which stabilize but do not of themselves appear to materially affect workability include mono-nitroresorcin, dinitroresorcin and para-nitro-phenol. Oxalic acid improves workability without a material-eil'ect on stability.

Examples of the use of trinitroresorcin in lead nitrato-hypophosphite priming mixtures are:

'It will be understood that both the ingredients and the proportions given in the above table are susceptible to wide variations. The quantity of nitro m-cresol, trinitrobenzoic acid or hypophosphorous acid may be substituted for the trinitroresorcin in substantially equi-molecular proportion, and such substitution will improve the stability and workability of the priming mixture.

By the substitution of mono-nitroresorcin or paranitrophenol in equi-molecular proportions for the trinitroresorcin in any of the examples, the mixture has improved stability after being subjected to warm, moist air.

In the above examples it was also found that by the substitution of oxalic acid in equi-molecular proportions for the trinitroresorcin, the workability was improved and stickiness prevented.

It is to be understood, of course, that more than 10% of the above mentioned substances may be used, provided the mixture is such that mass detonation" does not occur.

It is necessary that the substances used to stabilize or improve the workability of the priming mixture be ones that do not destroy any of the constituents thereof.

It was found, microscopically, that the use of resorcin, for example, does not apparently directly enter into the lead nitrato-hypophosphite because the double salt can be identified after;

' the'addition of trinitroresorcin.

In the manufacture of lead nitmto-hypophosphite, the double salt dries in a hard difflcult and dangerous to handle. The addition of trinitroresorcin, for example, prevents this hardening and makes it possible to safely manufacture and handle the double salt by itself. Examination under the microscope shows a characteristic long needle growth of the double salt,

and this is prevented by the addition of trim-- troresorcin, for example.

A means of placing trinitroresorcin in a priming mixture containing lead styphnate is to add -a strong mineral acid thereto or an acid stronger than trinitroresorcin. Whenthis is done, probably a suflicientamount of trinitroresorcin is liberated from the lead styphnate to be eflective in the stabilization and/or workability improvement 01' the priming mixture.

In the foregoing description, the use of certain stabilizers and workabflity-improving agents has been described in conjunction with priming compositions having certain ingredients therein, but it is to be distinctly understood that the invention is not limited thereto, nor to the proportions given, except as set forth in the appended claims.

trinitroresorcin or equivalent substance if of an explosive character is limited only by its tendency to cause mass detonation, and a practical measure is the ratio of the addition agent to the lead nitrato-hypophosphite resulting from the combination of the lead nitrate and lead hypophosphite. If the addition agent is trinitroresorcine the amount present should not exceed about 10% of the content of lead nitrato-hypophosphite.

In the above examples the trinitroresorcin improve the work- In any of the above examples, picric acid, tri- It is also to beunderstood that the reference to rimflre shells" or shells" is merelyan illustration-of the use of the invention and that the invention is applicable to the mixtures described regardless of their use, and is equally advantageous in the filling of center fire or shot shell primers or anywhere the material is handled. It is quite evident that the quantities of the diiferent ingredients oi the priming mixtures or equivalent ingredients maybe used, and because by this invention a way has been found to use successfully such a priming mixture,

to be broadly construed. I

form that is' the appended claims are What is claimed is:

1 In the manufacture of ammunition priming compositions by the wet mixing of ingredients including lead nitrate and lead hypophosphite, the method of improving the workability of the wet mixture and the stability of the finished mixture under storage which comprises adding thereto a tri nitro hydroxy benzolduring mixing.

2. In the manufacture of an ammunition priming composition comprising ingredients which include lead nitrato-hypophosphite, the method of improving workability in mixing and increasing improving workability in mixing and increasing stability under storage which comprises the addition of trinitroresorcin during mixing.

5. In the manufacture of an ammunition priming composition comprising ingredients which include lead nitrato-hypophosphite, the method of improving workability in mixing and increasing stability under storage which comprises the addi tion of picric acid during mixing.

,6. In the manufacture of an ammunition priming composition comprising ingredients which include lead nltrato-hypophosphite, the method of improving workability in mixing and increasing stability under storage which comprises the addition of trinitro meta cresol during mixing.

7. An ammunition priming composition of ingredients and proportions substantially as follows:

. Per cent Lead hypophosphite 8 to 10 Lead nitrate 10 to 12 Lead styphnate; 28 to 33 V Barium nitrate 14 to 23 /2 Glass Trinitroresorcin .5 to 2 GORDON M. CALHOUN. 

